Anodic oxidation of epitaxial superconductor-semiconductor hybrids
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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Anodic oxidation of epitaxial superconductor-semiconductor hybrids. / Drachmann, Asbjorn C. C.; Diaz, Rosa E.; Thomas, Candice; Suominen, Henri J.; Whiticar, Alexander M.; Fornieri, Antonio; Gronin, Sergei; Wang, Tiantian; Gardner, Geoffrey C.; Hamilton, Alex R.; Nichele, Fabrizio; Manfra, Michael J.; Marcus, Charles M.
I: Physical Review Materials, Bind 5, Nr. 1, 013805, 25.01.2021.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Anodic oxidation of epitaxial superconductor-semiconductor hybrids
AU - Drachmann, Asbjorn C. C.
AU - Diaz, Rosa E.
AU - Thomas, Candice
AU - Suominen, Henri J.
AU - Whiticar, Alexander M.
AU - Fornieri, Antonio
AU - Gronin, Sergei
AU - Wang, Tiantian
AU - Gardner, Geoffrey C.
AU - Hamilton, Alex R.
AU - Nichele, Fabrizio
AU - Manfra, Michael J.
AU - Marcus, Charles M.
PY - 2021/1/25
Y1 - 2021/1/25
N2 - We demonstrate a new fabrication process for hybrid semiconductor-superconductor heterostructures based on anodic oxidation (AO), allowing controlled thinning of epitaxial Al films. Structural and transport studies of oxidized epitaxial Al films grown on insulating GaAs substrates reveal spatial nonuniformity and enhanced critical temperature and magnetic fields. Oxidation of epitaxial Al on hybrid InAs heterostructures with a conducting quantum well show similarly enhanced superconducting properties transferred to the two-dimensional electron gas (2DEG) by proximity effect, with critical perpendicular magnetic fields up to 3.5 T. An insulating AlOx film that passivates the heterostructure from exposure to air is obtained by complete oxidation of the Al. It simultaneously removes the need to strip Al which damages the underlying semiconductor. AO passivation yielded 2DEG mobilities two times higher than similar devices with Al removed by wet etching. An AO-passivated Hall bar showed quantum Hall features emerging at a transverse field of 2.5 T, below the critical transverse field of thinned films, eventually allowing transparent coupling of quantum Hall effect and superconductivity. AO thinning and passivation are compatible with standard lithographic techniques, giving lateral resolution below
AB - We demonstrate a new fabrication process for hybrid semiconductor-superconductor heterostructures based on anodic oxidation (AO), allowing controlled thinning of epitaxial Al films. Structural and transport studies of oxidized epitaxial Al films grown on insulating GaAs substrates reveal spatial nonuniformity and enhanced critical temperature and magnetic fields. Oxidation of epitaxial Al on hybrid InAs heterostructures with a conducting quantum well show similarly enhanced superconducting properties transferred to the two-dimensional electron gas (2DEG) by proximity effect, with critical perpendicular magnetic fields up to 3.5 T. An insulating AlOx film that passivates the heterostructure from exposure to air is obtained by complete oxidation of the Al. It simultaneously removes the need to strip Al which damages the underlying semiconductor. AO passivation yielded 2DEG mobilities two times higher than similar devices with Al removed by wet etching. An AO-passivated Hall bar showed quantum Hall features emerging at a transverse field of 2.5 T, below the critical transverse field of thinned films, eventually allowing transparent coupling of quantum Hall effect and superconductivity. AO thinning and passivation are compatible with standard lithographic techniques, giving lateral resolution below
KW - CRITICAL MAGNETIC-FIELD
KW - TRANSITION
KW - TEMPERATURE
KW - FILMS
U2 - 10.1103/PhysRevMaterials.5.013805
DO - 10.1103/PhysRevMaterials.5.013805
M3 - Journal article
VL - 5
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 1
M1 - 013805
ER -
ID: 258712678